Eye Info

Charles Bonnet Syndrome

Summary: Designed to help you understand more about your eye condition, this guide has been written by our experienced eye health team.

• What is Charles Bonnet syndrome?
• Who is affected by Charles Bonnet Syndrome?
• What causes Charles Bonnet syndrome?
• Don’t only “mad” people see things?
• What kind of things do people see?
• What are the effects of the hallucinations?
• Is there a cure for Charles Bonnet syndrome?
• Sources of support
• Further reading

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What is Charles Bonnet syndrome?

Charles Bonnet syndrome (CBS) is a term used to describe the situation when people with sight problems start to see things that they know aren’t real. Sometimes called “visual hallucinations”, the things people see can take all kinds of forms, from simple patterns of straight lines to detailed pictures of people or buildings.

A Swiss philosopher named Charles Bonnet first described this condition in 1760 when he noticed that his grandfather, who was almost blind, saw patterns, figures, birds and buildings that were not there. Although the condition was described almost 250 years ago, it is still largely unknown by ordinary doctors and nurses. This is partly because of a lack of knowledge about the syndrome and partly because people experiencing it don’t talk about their problems from fear of being thought of as mentally ill.

Who is affected by Charles Bonnet Syndrome?

Charles Bonnet syndrome affects people with serious sight loss, and usually only people who have lost their sight later in life, but can affect people of any age, often appearing after a period of worsening sight. The visual hallucinations often stop within a year to 18 months.

What causes Charles Bonnet syndrome?

At the moment little is known about how the brain stores the information it gets from the eyes and how we use this information to help us create the pictures we see. There is some research that shows that when we see, the information from the eyes actually stops the brain from creating its own pictures. When people lose their sight, their brains are not receiving as many pictures as they used to, and sometimes new fantasy pictures or old pictures stored in our brains are released and experienced as though they were seen. These experiences seem to happen when there is not much going on, for example, when people are sitting alone somewhere quiet that is familiar to them or when they are in lying in bed at night.

Don’t only “mad” people see things?

It is normal for people who start to see things to worry about there being something wrong with their minds. Seeing things is often a sign of mental illness and the threat of Alzheimer’s can be a worry. People often keep quiet about their hallucinations for fear that others will think they are losing their minds. It is important to realise that failing eyesight and not any other mental problems normally causes CBS.

There are other medical problems that can cause people to see things, Parkinson’s disease, Alzheimer’s, strokes and other brain conditions that effect that part of the brain concerned with seeing. Having CBS does not mean that you are more likely to develop any of these other conditions.

Another difference between the hallucinations that people with mental health problems and those with CBS have is that in CBS people quickly learn that the hallucinations, although vivid, are not real. However, people with a mental illness have trouble telling the difference between their hallucinations and reality, and will often come up with complicated explanations for the things they are seeing (sometimes called a “delusion”). If you think you are having CBS hallucinations, tell your GP about them. You may find it useful to take a copy of this webpage along with you to show to your doctor.

What kind of things do people see?

There seem to be two different kinds of things people see. Both of them can be black and white or in colour, involve movement or stay still, and they can seem real, for example, cows in a field, or unreal, such as pictures of dragons.

Firstly, there are the hallucinations of patterns and lines, which can become quite complicated like brickwork, netting, mosaic or tiles.

Secondly, there are more complicated pictures of people or places. Sometimes whole scenes will appear, such as landscapes or groups of people, which are sometimes life-size, and at other times are reduced or enlarged in size. These pictures appear “out of the blue” and can carry on for a few minutes or sometimes several hours. Many people begin to recognise similar things appearing in their visions such as distorted faces or the same tiny people in particular costumes. Generally the pictures are pleasant although the effects can be scary.

What are the effects of the hallucinations?

Sometimes the complicated pictures can make it difficult to get around. For example, streets and rooms may have their shape changed or brickwork and fencing appear directly in front of you making it difficult to judge exactly where you are and whether you can walk straight ahead. One man describes how, approaching the top of the stairs, he had a vision of being on top of a mountain, and had considerable problems getting down the stairs. Good knowledge of your surroundings can help overcome this particular problem.

The complicated pictures can sometimes be a little scary. Although the visions themselves may not be of anything frightening, it is disturbing to start seeing strangers in your home or garden. People often overcome this by getting to know the figures in their visions. Another man describes how, when he wakes up in the morning, he says to the figures he is seeing: "Right, what have you got in store for me today?" This allows him to have some control over the way he feels about his seeing things.

Is there a cure for Charles Bonnet syndrome?

For most people, just knowing that it is poor vision and not mental illness that causes these problems is the best treatment, helping to understand and come to terms with them. Generally, these experiences will disappear after about a year or 18 months but, of course, this will not happen for everyone with this problem. For those with serious disturbing hallucinations, a number of medications are available. Unfortunately, none are effective for everyone.

One way of dealing with visions, when they occur, is to try to change things to see if this will help them disappear. For example, if they happen in the dark, then try switching a light on or if they happen in the light, try switching the light off. If they happen when you are sitting down, try standing up. Some people find that moving their eyes helps (for example, from left to right or up and down)

Sometimes talking over feelings with a counsellor, psychologist or psychiatrist can help provide people with ways of coping with the visions. If you are having problems with yours, talking to your GP may be a good way to find some help. Although CBS is not connected to mental health problems, the professionals in this field are the experts at helping people deal with hallucinations. If you are very distressed by your hallucinations, then your GP may want to refer you to the local mental health team. You may want to think about contacting RNIB’s Emotional Support Telephone Service.

Sources of support

At the moment RNIB is not aware of any specialised support group for people affected by CBS. However, there is a lot of general support for people affected by serious sight loss.

RNIB

RNIB has been offering support to people with severe sight loss for over 125 years and information about our 60 services is available from:

RNIB
105 Judd Street
London
WC1H 9NE

Telephone 0845 766 9999 or 020 7388 2525
(Some callers may find it cheaper to call a landline, so we have detailed both 08 prefixed numbers and landline equivalents where available.)

For information about local support groups for people with sight problems see our Local Agencies database.

RNIB does not comment on every trend or development but, when a treatment becomes established / recognised, we revise our website material to include it.

Partially Sighted Society

The Partially Sighted Society is able to give advice on coping with sight loss and they can be contacted at:

Partially Sighted Society
7-9 Bennetthorpe
Doncaster
South Yorkshire
DN2 6AA
Telephone 0844 477 4966

For more information on Charles Bonnet syndrome please contact:

Dr Dominic ffytche
Senior lecturer
Centre for Neuroimaging Sciences
Institute of Psychiatry PO89
De Crespigny Park
Denmark Hill
London
SE5 8AF

Telephone 020 32 28 30 64 (direct)
Telephone 020 32 28 30 60 (secretary)
Fax 020 32 28 21 16

Further reading

• Tuenisse et al. Visual hallucinations in psychologically normal people: Charles Bonnet Syndrome. The Lancet; vol347; March 23; 1996
• Menon GJ, Rahman I, Menon SJ, Dutton GN. Complex visual hallucinations in the visually impaired: the Charles Bonnet Syndrome. Surv Ophthalmol 2003; 48: 58-72.
• ffytche DH. Visual hallucinations and the Charles Bonnet Syndrome. Current Psychiatry Reports 2005; 7: 168-179.

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RNIB Eye Health Information Service

Last updated Nov 2007

Content author: eyehealth@rnib.org.uk

Last updated: 06/03/2008 15:41